Novel products from oxidation of the norditerpenoid alkaloid pseudaconine with HIO4.

Oxidation of pseudaconine 8, a norditerpenoid alkaloid, with HIO4 led to a series of novel interesting products, depending greatly on reaction medium and work-up conditions. Treatment of 8 in MeOH-H2O (1:1) with NaIO4 gave compounds 10 and 11, but compound 12 was obtained quantitatively when the final reaction solution was alkalized with conc. NH4OH. The imine 12 was also obtained in 100% yield by treating 8 in 5% HCl solution with NaIO4 followed by alkalizing the reaction products to pH>9 with conc. NH4OH. When the work up pH was 7-8, only N,O-mixed acetal-ketal 13 was formed in 96% yield, which was converted quantitatively to 12 by further alkalizing. When the reaction mixture was alkalized to pH 7-8 with Na2CO3, a hemiacetalketal 14 was afforded quantitatively, which was converted to 15 in 87% yield by further treatment with Na2CO3 or 5% NaOH methanol. Compound 15 could be converted back to 14 by treatment with 10% HCl solution. Acetylation of the imine 12 gave the compounds 16 and 17 in 15% and 19% yields, respectively. All of the new compounds were isolated and fully characterized.     

Synthesis of 2,3-dihydrobenzofuran-3-spiro-4′-dihydropyridines

2,3-Dihydrobenzofuran-3-spiro-4′-dihydropyridines are readily available via intramolecular addition of enolates to pyridinium ions.     

Structures of two oxidation products obtained from palytoxin

The structures of two oxidation products of N-(p-bromobenzoyl)palytoxin were unambiguously determined by means of X-ray crystallographic analysis.     

A CNDO/BW study of the structures of 2-substituted 3-aminoindene-1-spiro-2-thiirane and 3-oxoindane-1-spiro-2-thiirane

Conclusions CNDO/BW methods have been used to deduce the optimal conformations for 2-methylsubstituted 3-oxoindane-1-spiro-2-thiirane and 3-aminoindane-1-spiro-2-thiirane. The low reactivity of the sulfur atom in the spiroindane-substituted thiiranes is the result of steric shielding of the reaction center by the C² substituent. Thermal cleavage of the spiroindene-substituted thiiranes traces back to the fact that the increase in the total energy of the molecule is considerably less here than in the cleavage of the spiroindane-substituted analogs.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1265–1269, June, 1979.     

Determination of hydrogen peroxide by xenon trioxide oxidation

Aqueous xenon trioxide solution has been used as the oxidizing agent in three precise methods of analysis for hydrogen peroxide. A catalytic method, which utilizes hydrogen peroxide to initiate the reaction between t-butanol and xenon trioxide, is described for determining amounts of hydrogen peroxide as low as 0.9 microg or 36 parts per milliard (ppM). A direct spectrophotometric titration was found to have a lower limit of about 50 microg, or 20 ppM. An indirect titrimetric method was also used to determine hydrogen peroxide in amounts as low as 50 microg with a relative standard deviation of 4% which decreased to 1 % for amounts over 200 microg.     

Conformational analysis of cyclic sulphites. 2-Oxo 1,3,2-dioxathiane-4-spiro-4-tert-butyl-cyclohexanes

Three series of 4-spirosulphites, a new class of cyclic sulphites, were synthesized and five couples of diastereoisomers isolated. Their structural analysis, using ¹H NMR coupling constants and SO stretching vibration as conformational probes, shows a large variety of ananchomeric chair forms and multicomponent equilibria for the cyclic sulphite moiety, the cyclohexane part of the molecule remaining in the chair form. Related to the occurrence of severe interactions involving the 5-methyl or 6-tert. butyl substituent, several twist forms were encountered, with 2,5-axis and isoclinal SO or 1,4-axis and axial or equatorial SO as a consequence of the weak free energy difference between chair and twist conformations in the cyclic sulphite series.     

N,N'-dimethylformamide-derived products from catalytic oxidation of 3-hydroxyflavone

The biomimetic conversion of 3-hydroxyflavone in the presence of a copper(II) catalyst, dioxygen, and N,N'-dimethylformamide to oxidation products as well as two previously unreported solvent-derived products is seen. The two solvent-derived products were characterized, and their crystal structures were determined.     

Investigation of hydrolysis products from uranium trioxide and uranyl salts by derivatography and infrared spectroscopy

Summary It can be established from the data obtained by derivatography and infrared spectroscopy that the hydrolysis of- and amorphous UO₃ at room temperature, and that of uranyl salts in the presence of anion exchange resins, leads to compounds of UO₃ · 2H₂O composition with identical properties. This type of compound is of complex structure containing in addition to water molecules in two kinds of bonds, hydroxyl groups as well. The relative quantities of the components with different bond strengths show that the molecular structure can be described only by a trimeric formula, or by a formula corresponding to an integral multiple of a trimeric form. One kind of water has diffuse bond strength and is probably water between individual layers, while the other is a structural water of definite bond strength which may form various hydrogen bridge bonds.

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Zusammenfassung Aus derivatographischen und IR-spektroskopischen Untersuchungen ergab sich, daß die Hydrolyse von-UO₃ und amorphem UO₃ bei Zimmertemperatur sowie die Hydrolyse von Uranylsalzen in Gegenwart von Anionenaustauschharzen zu Verbindungen der Zusammensetzung UO₃ · 2H₂O führt, die identische Eigenschaften haben. Dieser Verbindungstypus hat komplexe Struktur und enthält außer Wassermolekülen mit zwei verschiedenen Bindungsarten auch Hydroxylgruppen. Die relativen Mengen der verschieden fest gebundenen Komponenten zeigen, daß die Molekülstruktur nur durch eine trimere Formel wiedergegeben werden kann. Ein Teil der Wassermoleküle ist diffus gebunden. Dabei handelt es sich wahrscheinlich um solche zwischen einzelnen Schichten. Die anderen sind strukturell gebunden und dürften verschiedene Wasserstoffbrücken ausbilden.

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Résumé On a pu établir, à partir de données obtenues par dérivatographie et spectroscopie infrarouge, que l'hydrolyse de UO₃ et amorphe à température ambiante, ainsi que celle des sels d'uranyle en présence de résines échangeuses d'anions, conduisait à des composés de composition UO₃ · 2H₂O aux propriétés identiques. Ce type de composé est de structure complexe, contenant en plus de molécules d'eau correspondant à deux sortes de liaisons, également des groupes hydroxyles. Les quantités relatives de composants possédant des forces de liaison différentes montrent que la structure moléculaire ne peut être représentée que par une formule trimère, ou par une formule correspondant à un multiple entier d'une forme trimère. L'une des sortes d'eau possède une force de liaison diffuse et il s'agit probablement d'eau placée entre des couches individuelles, tandis que l'autre est de l'eau structurale, avec une force de liaison définie, pouvant former diverses liaisons par pont d'hydrogène.

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This paper was presented at the Symposium on Analytical Chemistry held in Graz, 29th September–1st October 1965.     

Titrimetric determination of some organic acids by xenon trioxide oxidation

Aqueous xenon trioxide in acidic or neutral solutions oxidises carboxylic acids quantitatively to carbon dioxide and water. Micro and semimicro amounts of carboxylic acids may be determined by the iodometric titration of the excess of xenon trioxide remaining in the reaction mixture. The optimum time and temperature for the reaction depend on the structure of the acid ; dicarboxylic and hydroxy-carboxylic acids react faster than corresponding monocarboxylic acids. Oxalic and polyhydroxy acids are oxidised within 20 min at room temperature while acetic, maleic, succinic, malonic acids require 2 hr at 40 degrees . Carboxylic acids in amounts less than 100 mug are determined with a coefficient of variation of 4%, which decreases to 1 % for amounts over 250 mug.     

Novel products from attempted michael addition to 1-methyl-1,2,5,6-tetrahydropyridine-4-carbonitrile

The reaction of some phenols with the title compound, in the presence of sodium, gives 2-(2-hydroxyaryl_piperidine derivatives. Geometrical isomers have been separated, which differ in having an equatorial (A) or axial (B) cyano group on the piperidine chair (the methyl and aryl groups are equatorial in both forms). The x-ray crystallographic structures of an example of each of A and B are reported and the proton NMR spectra are assigned.     

机械活化木薯淀粉氧化产物的结构表征

采用搅拌球磨机对木薯淀粉进行机械活化,以活化60min的木薯淀粉为原料,CuSO4为催化剂,H2O2为氧化剂干法制备氧化淀粉。利用红外光谱、扫描电子显微镜、X-射线衍射等手段对产物的结构进行表征分析,并与原淀粉的氧化产物进行比较。结果表明,机械活化对木薯淀粉的氧化反应有显著的影响。原木薯淀粉的氧化反应主要发生在淀粉颗粒的表面及无定形区,部分发生在结晶区,产物是无定形及结晶状态的结构;活化淀粉的氧化反应在淀粉团粒表面及内部均匀进行,产物是无定形的聚集状态结构。并就机械活化对淀粉氧化的强化机理进行了探讨。